Slater-type orbitals (STOs) possess the cusp and long range decay present in atomic wave functions. However, analytic integrals are not known for STOs which has limited their use in quantum chemistry. We have developed SlaterGPU, a GPU-accelerated library written in OpenACC for computing the 1- and 2-electron STO integrals over atomic grids. To facilitate numerical integration, the electron repulsion integrals are computed using the resolution-of-the-identity (RI) approximation, allowing the 6-dimensional, 4-center integrals to be expanded in terms of 3-dimensional, 3-center integrals. The use of 3D grids instead of 6D grids makes the grid size tractable and is highly amenable to evaluation on GPU due to the large number of parallel execution of the GPU architecture. An initial implementation results in a speedup greater than 80x over CPU for evaluating 3-center integrals. Parallelization across multiple GPUs allows STO integral throughput to be competitive with single-threaded Gaussian integrals. In this presentation, we discuss strategies for achieving high performance and benchmark calculations using wave function theories, such as full configuration interaction, to demonstrate the speed and accuracy of the STO integral library.

GPU-accelerated numerical integration of electron repulsion integrals in a Slater basis

ACS Spring 2022

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